Public bug reported:
Hardware:
Laptop: Dell Latitude E7450
GPU: Intel HD Graphics 5500 (Broadwell)
Graphics driver: i915
Ubuntu: 24.04 LTS
Working kernel:
6.17.0-40-generic
Broken kernel:
7.0.0-28-generic
Expected behavior:
Brightness slider changes the physical backlight.
Night Light applies the display color temperature.
Actual behavior:
Brightness slider moves and the value in
/sys/class/backlight/intel_backlight/brightness changes, but the display
brightness never changes.
Night Light has no visible effect.
Windows controls brightness correctly on the same hardware.
Troubleshooting performed:
- Tested GNOME and KDE Plasma.
- Tested Wayland.
- intel_backlight interface exists.
- i915 driver is loaded.
- OpenGL acceleration works.
- Brightness works immediately after booting 6.17.0-40.
- Brightness fails again after booting 7.0.0-28.
This appears to be a kernel regression between 6.17 and 7.0.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-40-generic 6.17.0-40.40~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-40.40~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-40-generic x86_64
ApportVersion: 2.28.2-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: bikalpa 3800 F.... wireplumber
/dev/snd/controlC0: bikalpa 3800 F.... wireplumber
/dev/snd/seq: bikalpa 3793 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: KDE
Date: Mon Jul 20 10:45:32 2026
InstallationDate: Installed on 2025-08-04 (349 days ago)
InstallationMedia: Ubuntu 24.04.2 LTS "Noble Numbat" - Release amd64 (20250215)
MachineType: Dell Inc. Latitude E7450
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-40-generic
root=UUID=b2160186-f194-4ed0-a101-032701073fed ro quiet splash
video.use_native_backlight=1 vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.17.0-40-generic N/A
linux-backports-modules-6.17.0-40-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/25/2019
dmi.bios.release: 65.23
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A23
dmi.board.name: 0D8H72
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvrA23:bd11/25/2019:br65.23:svnDellInc.:pnLatitudeE7450:pvr:rvnDellInc.:rn0D8H72:rvrA01:cvnDellInc.:ct9:cvr:sku062E:
dmi.product.name: Latitude E7450
dmi.product.sku: 062E
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Assignee: bikalpa pandey (bikki-1)
Status: New
** Tags: amd64 apport-bug noble
** Changed in: linux-hwe-6.17 (Ubuntu)
Assignee: (unassigned) => bikalpa pandey (bikki-1)
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https://bugs.launchpad.net/bugs/2161283
Title:
Screen brightness and Night Light do not work when booting Linux
kernel 7.0.0-28-generic.
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